Find Blender PNG (or other format) Metadata in Adobe
I just tried XNViewMP and it seems to be able to read Blender's metadata on both JPG and PNG Files.

JPEG seems to be using several comment fields, as opposed to PNG which uses dedicated ones for each information. It does save a File field with the name of the original Blend file it was rendered from, so if you had them saved under different locations while rendering from different computers you should be able to identify which files were from the wrong file from there I think.

XNViewMP has some search functionalities, maybe it can search EXIF info, not sure. Anyway it uses EXIFTool to extract this information, so if that fails maybe you could go there directly if XNView doesn't work for you.

Edit: Just to be clear, in XNView, open your image view and under view mode while previewing the image file right click on the image and select Properties then check the ExifTool tab